• Journal of Electrical Engineering and Technology
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• v.4 no.3
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• pp.382-388
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• 2009

Recently, hydrogen energy has been anticipated to change the paradigm of conventional power systems because it can expand sustainable energy utilization and conceptually provide remarkable flexibility to power system operation. Since hydrogen energy can be converted to electric energy through fuel cells, fuel cells are expected to play an important role in the future hydrogen economy. In this paper, a Proton Exchange Membrane Fuel Cell (PEMFC) is modeled as an equivalent circuit and its steady-state characteristics investigated using the model. PEMFCs can be connected to power systems through power conditioning systems, which consist of power electronic circuits, and which are operated as distributed generators. This paper analyzes the effects of the characteristics of the PEMFC internal voltages and investigated the dynamic responses of the PEMFC under fault conditions. The results show that the fault current contribution of the PEMFC is different from those of conventional generators and is closely related to its operating point.

• Journal of Advanced Marine Engineering and Technology
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• v.37 no.3
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• pp.266-273
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• 2013

With the worldwide trend of controlling the utilization of fossil fuels inducing global climate change, many efforts will have to be made on securing a sustainable energy supply. Tidal current is a concentrated form of gravitational energy, its resource is significant, but limited locations. To effectively capture tidal current energy from the sea, a group of tidal turbines should be formed and positioned with optimal size and spacing for absorbing from multiple points. Thus, the flow field including turbines becomes a huge domain, a so-called tidal farm. It can be very convenient technically and economically if a whole turbine farm is simulated by means of actuator disc thoery. So, the analysis method using actuator discs coupled with a solution of Reynolds Averaged Navier-Stokes (RANS) equations is adopted for actual tidal turbines. Actuator discs have regions where similar forces imposed by actual turbines are applied to a flow. As working in group formation, turbines naturally have interaction effects on one another. Therefore, the present paper investigate the evaluation on the operating performance of tidal farm in terms of the mutual influence among turbine units with various lateral and longitudinal spacing. Authors expect that results of the present study contribute to the development of tidal farm for the future potential energy.

• Journal of Advanced Marine Engineering and Technology
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• v.29 no.8
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• pp.883-890
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• 2005

The industrial growth and the raised living quality have led to the massive energy consumption. As a result. the polluted environment and the limited amount of energy resources emerged as serious problems to be resolved in 21st century. Especially, in the case of Korea whose imported energy dependency rate is 98.2$\%$ in 2003 and constantly increasing every rear. more than 24$\%$ of overall energy consumption is for housing and commercial use. In order to cope with the shortage of natural energy resources, it is inevitable to develop alternative sustainable energy resources including seawater heat. so that they can replace existing resources. The heat transfer air velocity 3.5 m/s is proper to consideration with the body the pipe size 200A is more suitable than look due to the air velocity quantify and the ratio of pipe surface area. And the error between experimental data with simulation is below 5.34$\%$ so the suggested equation for calculating heat transfer capacity can be used. Therefore out of many methods utilizing seawater heat. this work Presents the efficiency of using sea water heat as a resource for air-conditioners which can be converted from the outside air through the air-to-heat conversion tube . Consequently. this method provides pretty reasonable energy efficiency.

• Journal of Energy Engineering
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• v.27 no.2
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• pp.81-88
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• 2018

Every day a huge amount of paper is being used, most of them are thrown after using. This directly impacts on the environment. Therefore, waste paper management is necessity to protect the environment from its annihilation and pollution. Paper recycling products consist of printing paper, newspaper, corrugated containers, magazine paper and so on. Reuse waste paper will reduce the consumption of wood and virgin pulp as recycling one ton of newsprint can save approximately 1 ton of wood, meanwhile recycling 1 ton of printing paper can save more than 2 tons of wood. With increasing recycling rates, lower quality paper fractions may be included. Thus the selection of a paper recycling technology is a crucial first design consideration. The paper recycling must be accompanied by appropriate technology to manage a huge volume of wastepaper. The specific objectives of this study were as follows: (1) comprehensive literature reviews of paper production and consumption, (2) figure out about paper recovery and utilization, (3) investigate the paper recycling in the sustainable times, (4) introduce eco-friendly recycling technology to paper industry.

• Computers and Concrete
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• v.12 no.6
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• pp.755-774
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• 2013

Considering the well known environmental issues of cement manufacturing (direct and indirect levels of $CO_2$ emissions), clinker replacement by supplementary cementing materials (SCM) can be a very promising first step in reducing considerably the associated emissions. However, such a reduction is possible up to a particular level of SCM utilization, influenced by the rate of its pozzolanic reaction. In this study a (4-step) structured methodology is proposed in order to be able to further adjust the concrete mix design of a particular SCM, in achieving additional reduction of the associated levels of $CO_2$ emissions and being at the same time accepted from a derived concrete strength and service life point of view. On this note, the aim of this study is twofold. To evaluate the environmental contribution of each concrete component and to provide the best possible mix design configuration, balanced between the principles of sustainability (low environmental cost) and durability (accepted concrete strength and service life ). It is shown that such a balance can be achieved, by utilising SCM by-products in the concrete mix, reducing in this way the fixed environmental emissions without compromising the long-term safety and durability of the structure.

• Environmental Engineering Research
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• v.25 no.2
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• pp.243-250
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• 2020

A down-flow hanging sponge (DHS) bioreactor was operated for the treatment of domestic wastewater. The Stover-Kincannon model was applied for kinetic evaluation of the reactor performance during the operational period. As a result, the coefficient of determination (R²) for straight lines of effluent concentration from the experimental data and from the predictive data of BOD₅; NH₄⁺-N; and TN were 0.9727; 0.9883; and 0.9934, respectively. The calculation of saturation value constant (Umax - g L^-1 d^-1) and maximum utilization rate constant (KB - g L-1 d-1) were 56.818 and 75.034 for BOD₅; 2.960 and 4.713 for NH₄⁺-N; 2.810 and 8.37 for TN, respectively. The study suggests that Stover-Kincannon model can be used for effective evaluation of kinetic removal of BOD₅; NH₄⁺-N; and TN from domestic wastewater treated in a DHS bioreactor.

• Computers and Concrete
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• v.10 no.2
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• pp.95-104
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• 2012

This study uses recycled green building materials based on a Taiwan-made recycled mineral admixture (including fly ash, slag, glass sand and rubber powder) as replacements for fine aggregates in concrete and tests the properties of the resulting mixtures. Fine aggregate contents of 5% and 10% were replaced by waste LCD glass sand and waste tire rubber powder, respectively. According to ACI concrete-mixture design, the above materials were mixed into lightweight aggregate concrete at a constant water-to-binder ratio (W/B = 0.4). Hardening (mechanical), non-destructive and durability tests were then performed at curing ages of 7, 28, 56 and 91 days and the engineering properties were studied. The results of these experiments showed that, although they vary with the type of recycling green building material added, the slumps of these admixtures meet design requirements. Lightweight aggregate yields better hardened properties than normal-weight concrete, indicating that green building materials can be successfully applied in lightweight aggregate concrete, enabling an increase in the use of green building materials, the improved utilization of waste resources, and environmental protection. In addition to representing an important part of a "sustainable cycle of development", green building materials represent a beneficial reutilization of waste resources.

• The Journal of Information Systems
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• v.14 no.2
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• pp.101-132
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• 2005

There is a need for research to identify the integrated, rather than fragmented, factors that determine users' acceptance of Internet shopping. Using the newly revised technology acceptance model (TAM) as a theoretical framework, this study investigates the effect of a set of information systems quality (information quality and system quality) and trust on intention to use Internet showing through perceived ease of use and perceived usefulness. Using structural equation modeling, the results strongly support the utilization of TAM in predicting users' intention to use Internet shopping, and demonstrates the effects of critical external variables on behavior intention through perceived ease of use and perceived usefulness. Systems quality such as response time, accessibility, and usability has significant effects on perceived ease of use of Internet shopping. Futhermore, trust has also a significant effect on perceived usefulness, perceived ease of use, intention to use Internet shopping, and actual usage of Internet shopping. Based on these results, this study suggests managerial implications of new Internet shopping strategies, focusing on the integration of information systems quality and trust in order to achieve sustainable competitive advantage in Internet shopping.

• The Research Journal of the Costume Culture
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• v.28 no.1
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• pp.131-145
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• 2020

As the population of consumers of outdoor wear expands, there is increasing interest among consumers in trendy lifestyle outdoor. Accordingly, it is essential to develop designs that are drawn from outdoor wear. This can be limited to traditional mountaineering suits, and designs developed from men's outdoor zip-up T-shirts, which are highly utilized in everyday life, are very important. This study developed the design of a summer zip-up T-shirt for men with both functional and aesthetic qualities. Visual images of foreign brands and domestic outdoor-focused T-shirts from the spring/summer seasons of 2013-2019 were collected to analyze the following modeling elements: silhouettes, details, colors, materials, and prints. In addition, the design concept was derived by analyzing presentations from the global outdoor trade Fairs (2013-2019). To develop a sustainable eco-friendly outdoor summer T-shirt for men, the concept was derived according to three categories: eco-friendly, sportism-expressed active elements of sports, and an outro-concept of urban town wear as an outdoor lifestyle. Thus, a total of 12 styles of design were developed. High utilization of the outdoor wear T-shirts (which are also popular as lifestyle wear), is an important aspect of building a segmented lineup of the slow-growing outdoor wear market and supports expansion of the scope of theoretical research on outdoor wear design.

• Journal of the Korean Institute of Landscape Architecture
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• v.27 no.3
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• pp.69-79
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• 1999

Recently, new concept and paradigm of 'Environmentally-Friendless' is taking a growing interest in environmental planning and design. This study is to develop the new approach of sustainable development, and to establish the indicators for environmentally-friendliness of "Tourism Farms" in rural areas. A questionnaire survey was conducted for deputy manager group and expert group. The environmentally-friendliness of tourism farms is composed of three categories, conservation of global environment(Low Impact), friendliness to surrounding nature(High Contact), and environmental health and amenities (Health '||'&'||' Amenity). Four indicators, such as saving of energy and water resource, reduction and reuse of garbage, natural purification of sewage disposal, and utilization of natural energy, were affecting the first category, i.e., conservation of global environment(Low Impact). And, friendliness to surrounding nature (High Contact) is affected by 3 indicators, such as contact to nature and diverse green areas, water intimate '||'&'||' contact areas, and natural ecology observation by biotope. Finally, the dimension of environmental health and amenity is affected by 3 indicators, such as nature affinity by farming experience, environmental-friendliness of soil '||'&'||' crops by organic farming, campaign and education programs of environmentally-friendliness. From the result of Importance-Performance Analysis(IPA) for 10 indicators, environmentally-friendliness was recommended as 'Concentrate Here'. And, the content validity of 10 indicators for 3 categories was examined by factor analysis. The result showed as the same as hypothetical model, which proved the validity of hypothetical model.